OK, I admit, I am at least partially responsible for having set off the debate around terminology, for which I am profoundly sorry.
Bethberry is, as so often, entirely correct that we shouldn't get bogged down in a discussion of definitions -- using the correct words is important, sure, but I'd be far more interested in seeing what Tolkien's book
does and how it does it, than worrying about what to label it.
So, whether we call Tolkien's style "myth," "allegory," "epic" or "Fred", what's the effect of that style on our interpretation of the whole?
In other words -- what
Durelin said!
In an effort to open this thread up a bit further (and avoid heading once more down the canonicity road. . .
) -- I would really like to hear what other people think Tolkien is identifying in the Foreward as the important themes of his work. As has been pointed out here, this foreward was written about 10 years after the appearance of LotR: what in that time has Tolkien decided his book is 'about'??